The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of the application.
Sliding windows of the kind envisaged by the present inventors are those that form a barrier between the interior and exterior of a building such as a house or apartment, or a commercial building. Sliding windows conveniently allow the window to be opened to allow air flow through the opening into or out of the building. A difficulty with sliding windows is that they can present various insulation problems, including that they are often difficult to seal and therefore are associated with undesirable airflow through or past parts of the window assembly that slide. This includes the sections of the sashes that overlap in the closed position of the sashes, i.e. the upper edge of a bottom sash and the lower edge of an upper sash.
Another insulation problem that exists with sliding windows is that of thermal conduction of both heat and cold between the inside and outside the building to which the windows are fitted. For this reason, sliding windows have included thermal breaks in the window construction between outside facing portions of a window and inside facing portions, in order to disrupt the conduction of heat or cold through the window from outside to inside and vice versa.
The use of thermal breaks can have a positive effect on the insulation properties of a building, but the manner in which thermal breaks have been provided to date has caused difficulties in maintaining the aesthetic appearance of a window, as well as causing difficulties in the manufacture of the components in which the thermal breaks are provided. The present inventors have recognized a need for an improved sliding window assembly to allow the inclusion of thermal breaks in windows either without affecting, or at least reducing the effect of the appearance of the window and/or to enable the components in which the thermal breaks are provided to be more easily manufactured and assembled compared with the prior art.